Well it's been pinned so go ahead and start updating your original post.
As far as adding fog lights to the Sierra, that write up above is for Silverado's as far as I know. Installation on the Sierra's should be really easy and wiring should be the same as the Silverado's wiring.
Not on this site but good writeup:
How to remove/replace GMC GMT900 grill
http://www.truckmodcentral.com/forums/showthread.php?t=1091
http://www.truckmodcentral.com/forums/show...t=billet+grille
GMT900 Projector Headlight Writeup
http://www.gm-trucks.com/forums/index.php?...mp;hl=headlight
Bed Underrail Lighting
http://www.gm-trucks.com/forums/index.php?showtopic=93508
Custom Sheet Metal Gap Guards
http://www.gm-trucks.com/forums/index.php?...=81181&st=0
Install/Change door handles
http://www.gmfullsize.com/forum/showthread.php?t=93769